apply_at_region

Apply an arbitrary Pool-to-Pool transform to the content of a named region, leaving the flanking sequences unchanged. The function receives the region’s content as a Pool and must return a Pool. By default region tags are removed from the output; set remove_tags=False to keep them.

import poolparty as pp
pp.init()

Parameters

Parameter	Type	Default	Description
`pool`	`Pool \| str`	(required)	The Pool to apply the transform to. Can also be a plain sequence string.
`region_name`	`str`	(required)	Name of the region whose content to transform.
`transform_fn`	`callable`	(required)	Callable `(Pool) -> Pool` applied to the region content. Examples: `lambda p: p.upper()`, `lambda p: p.rc()`, `lambda p: p.mutagenize(num_mutations=1)`.
`rc`	`bool`	`False`	When `True`, reverse-complement the region content before passing it to `transform_fn`, then reverse-complement the result back. Useful for minus-strand regions.
`remove_tags`	`bool`	`True`	When `True`, region tags are stripped from the output. When `False`, tags are preserved around the transformed content.
`iter_order`	`int \| None`	`None`	Dimension-name ordering for downstream multi-pool iteration.
`prefix`	`str \| None`	`None`	Prefix for the operation node name in the pool graph.

Note

Only the most commonly used parameters are shown above. For the full parameter list, see apply_at_region() in the API Reference.

Examples

Uppercase a soft-masked region

p.upper() lifts a lowercase region to uppercase without touching the flanking bases. Tags are removed by default.

wt         = pp.from_seq("AAAA<cre>atcg</cre>TTTT")
uppercased = pp.apply_at_region(wt, "cre", lambda p: p.upper())
uppercased.print_library()

uppercased: seq_length=12, num_states=1 AAAAATCGTTTT

Reverse-complement a region

p.rc() reverse-complements only the region content (ATCG becomes CGAT) while the flanking bases remain untouched.

wt      = pp.from_seq("AAAA<cre>ATCG</cre>TTTT")
flipped = pp.apply_at_region(wt, "cre", lambda p: p.rc())
flipped.print_library()

flipped: seq_length=12, num_states=1 AAAACGATTTTT

Keep region tags in output (remove_tags=False)

Set remove_tags=False to preserve the tag markup so the transformed region is still addressable by name downstream.

wt     = pp.from_seq("AAAA<cre>atcg</cre>TTTT")
tagged = pp.apply_at_region(wt, "cre", lambda p: p.upper(),
                            remove_tags=False)
tagged.print_library()

tagged: seq_length=12, num_states=1 AAAA<cre>ATCG</cre>TTTT

Mutagenize within a region

Any Pool operation can serve as the transform. Here mutagenize with mode='sequential' generates every single-base substitution inside the region while the flanks stay wild-type.

wt     = pp.from_seq("AAAA<cre>ATCG</cre>TTTT")
mutant = pp.apply_at_region(wt, "cre",
             lambda p: p.mutagenize(num_mutations=1,
                                    mode="sequential"))
mutant.print_library()

mutant: seq_length=12, num_states=12 AAAACTCGTTTT
AAAAGTCGTTTT
AAAATTCGTTTT
AAAAAACGTTTT
AAAAACCGTTTT ... (12 total)

See apply_at_region().